Antenna network for vehicle guiding systems



Aug 20, 1940 G. E. MMPERROUX 2,212,245

ANTENNA NETWORK FOR VEHICLE GUIDING SYSTEMS Filed May 27, 1938 Comma/fera@ @Ufff/Amy Patented Aug. 20, 194() ANTENNA NETWORK'k FOR VEHICLE GUIDING SYSTEMS George Edme Marcel Perreux,` Paris, France, assignor to International Standard Electric Corporation, New York, N. Y.

Application May 27, 1938, Serial No. 210,344 In France June-'11, 1937 6 Claims.

'Ihe present invention relates to directive antenna systems for guiding vehicles by radio-electric waves. l

The invention relates particularly to radio guiding systems in which an emitter is arranged for signalling by the method of complementary signals such as dots and dashes.

An object of the invention is the provision of an antenna system, particularly arranged for radio guiding of vehicles.

Another object of the invention is to provide means for varying the size of the directive channel.

In accordance with one of the features of the invention, the sharpness or slope of the radiation diagrams of the directional antenna is modified as desired,A without any displacement of the antenna elements.

In accordance with -another feature of the invention, means is provided for reducing considerably, or practically eliminating, the variations in the strength of the eld in the directive channel which are known as keying clicks or the clatter of the axis, and which are produced during operation.

In accordance with a further-feature of the invention, in an antenna system comprising an 40 bodiment of an antenna system incorporating the features of the invention;

Fig. 2 represents the radiation diagram corresponding to the system of Fig. 1 for one of the alternate operating periods;

Fig. 3 is a curve showing the influence of the coupling self-inductance of the lateral elements of Fig. 1 on the slope of the radiation diagrams;

Fig. 4 is a curve showing the angular displacement of the directive axis of the system of Fig. 1 as a function of the ratio of the coupling selfinductances of the lateral elements;

Fig. 5 represents a portion of the radiation diagrams of the system during the two altern-ate periods of operation and the dead time between the alternate operating periods;

(C1. Z50-I1) Fig. 6 represents an antenna system which includes means for eliminating the clatter of the directive axis; and,

Fig..7 represents an antenna element employed in the arrangement of Fig. 6. l

Referring to Fig. 1 of the drawing, three vertical antennae I, 2 and 3 are arranged in the same plane and spaced at a distance from each other equal to one quarter Wavelength of the operating wave. These antennae are supplied by a 10 source of high frequency energy (not shown) but connected by the lines 4 through a system of transmission lines (not shown), the transmission lines being balanced and provided, if necessary, with devices of any suitable known type for elim- -15 inating interfering currents. Transmission lines 5 and 6 connect the antenna I to antennae 2 and 3 respectively. These antennae 2 and 3 consist of two parts connected together by a self-inductance 1, 8 respectively, and each can be short- 20 circuited by its respective relay 9 or I0.

The central antenna I is continuously fed and the antennae 2, 3 are fed alternately, to producev the oscillating movement of the radiation diagram -about the directive axis. Let it be supposed 25 that the antenna 3 is fed at a certain moment. It consumes a quantity of power which is a function of the coupling between the self-inductance 8 and the transmission line 6 since the impedance of this line and the tuning of the antenna I are 30 not varied. Given that the line 6 is crossed the element 3 acts as an active reflector with regard to the radiation of the antenna I.

At the instant under consideration the relay 9 short-circuits the coupling self-inductance 'I of 35' the antenna 2 which is consequently not fed. Since at this moment however the electric length of the antenna 2 is less than a half-wavelength, this antenna 2 acts as a parasitic element and carries currents induced by I and 3 of such phase 40 that their action is added to that of 3. The element 2 operates in this case as a director. It should be observed that the closing of the relay 9 does not effect the central antenna I since the line 5 has a length of one quarter-wavelength. 45 The radiation diagram of the system in these circumstances is shown in Fig. 2. The diagram comprises a principal lobe I I and a minor lobe I2 with common tangents IY, IY'.

During the alternate period of operation the 50 functions of the lateral antenna are reversed; 2 is the reflector, 3 the director. The diagram of the system in these circumstances is similar to that shown in Fig. 2 and occupies a symmetrical position with respect to the axis IX. 55

The size of the overlapping parts of the radiation diagrams of the two alternate periods, or

the channel within which a continuous signal is obtained by the vehicle receiver, as is well known,

`is inversely related to the so-called sharpness of the diagrams, i. e. to the slope of the diagrams at their points of intersection with the axis IX. The slope of these diagrams is on the other hand a function of the angular distance between the direction IX and the axis of no radiation IY, this angle being indicated as I3 in the drawing. In accordance with one of the features of the invention, the slope of these diagrams can be regulated, and consequently the size of the channel Where the signal is a continuous dash,

may be adjusted by varying the angle XIY. The

adjustment can be accomplished by modifying an electric characteristic of the radiation from the lateral antennae 2 and 3, for instance, the phase or the intensity, or both the phase and intensity together. In the preferred embodiment of the invention, the lcoupling self-inductance of one or more of the lateral antennae is modified.

This coupling self-inductance operates on the slope of the diagrams in accordance with a law, represented in arbitrary units, by the curve Il of the Figure 3, where ordinates represent the slope of the radiation diagram and abscissae represent the tuning of the antennae 2 or 3. The useful part of the curve is shown at It.

Taking dissymmetrical values for the self-induotance coils 'i and 8, the directive axis of the antenna system may be turned within certain limits without displacing any mechanical element. Fig. 4 shows a curve it given by way of example, in which ordinates represent angular displacements of the directive axis and abscissae represent the coupling self-inductance.

In systems of the kind hereinbefore described it is impossible to maintain a strict coincidence between the closing of the relay contacts 9 and the opening of relay contacts Iii, and vice versa. rlhere is always a dead period during which the two relays are open (or closed). The electric eld on the directive axis or channel therefore takesfin this dead period a higher (or lower) value than its normal value and produces the phenomenon known as axis clatter.

In accordance with one feature of the invention the automatic manipulator is systematically arranged in such arnanner that the contacts of the two relays are closed during the dead period. The two lateral antennae during the dead period therefore function simultaneously as directors.

The line AB, Fig. 5 shows a portion of the radiation diagram corresponding to this dead period, whilst CD, CD represent parts of the useful diagrams of the alternate periods. The eld on the axis IX during the dead period, is consequently of a .lower value than that during the useful alternate periods. This disadvantage is overcome in accordance with a'feature of ie invention by arranging in front of the antenna I an antenna tl as shown in Fig. v6 and which is not fed with current. On account of the difference in the distances i-hi and 2in-Ill (or 3HE/1), the antenna it is more powerfully in fluenced by the central antenna i than by the lateral antenna.- 2 or 3. By adjusting the electrical length of the antenna ill it is possible to cause it to operate as director, that is to say, so that its field reinforces that of the central aintenna I in the direction EX. By suitably choosing the director eiiect of it it is possible to cause the three diagrams of Fig. 5' to intersect at a point. The result of this is that along the directive axis, the field strength remains constant and the axis crackings are eliminated.

In a preferred embodiment illustrated in Fig. 7, the linear length of the conductor I4 is made greater than a half of the operating wave length and the antenna ill is provided in its centre with a variable condenser I5 which permits the director eect' of I i to be easily adjusted, as for the purpose explained above. It would also be possible to adjust the length of a rectilinear conductor, or on the tuned self-inductance of a conductor which is linearly too short.

It will be understood that the arrangements described above which summarize the main features of the invention may be associated with known means such as director or reflector elements, whether fed or not, intended to improve the radiation characteristics in a predetermined direction.

What is claimedv is:

l. A radio directive antenna system for guid-I ing vehicles comprising an antenna element and first and second radiation distorting elements consisting of dipole units, said radiation distorting elements being positioned on either side of said antenna element to produce a desired shape of radiation diagram, a self inductance connecting the two parts of each radiation distorting element, means for short circuiting the self inductances of the first and second radiation distorting elements alternately to cause said first element to act alternately as reflector and director and said second element to act alternately as director and reflector in converse manner, a transmission line connecting all the said elements, and a source of exciting current connected to the antenna elements.

2. A radio directive antenna system for guiding vehicles comprising an antenna element, first and second radiation distorting elements, an auxiliary director element located to be chiey influenced 'by said antenna element, said rst and second radiation distorting elements each consisting of a dipole unit having two parts, a self induct'ance connecting the two parts of each of said first and second radiation distorting elements, means for short-circuiting the self inductances of said radiation distorting elements alternately to cause said first element to act alternately as reector and director and said second element to act alternately as director and reflector in converse manner, a transmission line connecting the antenna element to the first and ysecond radiation distorting elements, a source of exciting current connected to the antenna element, and means for varying the electrical length of said auxiliary director element.

3. A radio directive antenna system comprising a central dipole antenna element, two other dipole elements located on opposite sides of the antenna and at a distance therefrom equal to one quarter of the workin.or wavelength and each having two parts, self inductances connecting the two parts of each of the two other dipole elements, and relay means for alternately short circuiting said self-inductances, a transmission line connecting all three elements and crossed between adjacent elements, a source of exciting current connected to the said antenna element, a fourth dipole unit not connected to said transmission line and' located in a plane perpendicular to the plane containing the first mentioned three dipole elements, and at a distance from said central dipole antenna element equal to one half *5 5 ing vehicles comprising an antenna element, a

first and a second radiation distorting element, means for exciting said antenna element, a transmission line extending between said antenna element and each of said radiation distorting ele- 10 ments to cause such radiation distorting element to function as a fed radiator, means for alternately blocking the flow of power over said transmission line to said first and second radiation distorting elements to cause such radiation dis- 15 torting elements to function alternately as parasitic elements whereby said rst element functions as a fed radiator during the intervals in which said second element functions as a parasitic element, and conversely said second element functions as a fed radiator during the intervals in which said first element functions as a parasitic element.

5. A radio directive antenna system according to claim 4, wherein the electrical length of said radiation distorting elements when in condition for functioning as parasitic elements are so related to the wavelength with which the system is employed that such elements then act as directors, and wherein the transmission line between the antenna element and the radiation distorting elements are so connected that in the fed condition each such element acts as a fed reflector.

6. A radio directive antenna system according to claim 4, wherein each of said radiation distorting elements comprises a dipole divided into two parts and an adjustable non-radiating iinpedance connecting said two parts, and wherein said means for alternately blocking the flow of power to said radiation distorting elements comprises contacts connected to effectively eliminate each such impedance from its dipole simultaneously with the blocking of the flow of power to said dipole whereby by adjusting each said irnpedance the sharpness of the resultant pattern may be adjusted.

GEORGES EDME MARCEL PERROUX. 

